The long-term objective of this investigation is directed towards understanding more fully the potential mechanism(s) whereby membrane-bound enzyme interactions and virus-determined surface antigens influence lymphoid cell proliferation and malignant growth. This objective encompasses studies concerned with the following three interrelated problems: 1. Synthesis, assembly and expression of the Moloney leukemia virus-induced surface antigen (MCSA) on mouse lymphoma cells and in immunoresistant sublines; 2. Molecular differences in membrane from Epstein Barr virus (EBV) negative lymphoma lines and their in vitro EBV-transformed sublines; and 3. Covalent surface modification of human lymphoid cell lines. These objectives are a logical continuation of studies currently in progress and successful achievement will provide relevant information as to: 1. How MCSA, a tumor-specific surface antigen, is involved in the control and prevention of oncovirus-directed tumors. Structural alterations in this antigen are associated with immunoresistance. 2. How an EBV directed membrane antigen (MA) may be related to the proliferative transforming interaction of virus and lymphocytes. 3. How the regulatory function of phosphorylation and sialylation of surface macromolecules may related to proliferation and/or somatic cell modification of MA. MA may be functionally relevant to the immunological restriction of tumor growth. Since many alterations in the cell surface have been implicated in malignant growth, knowledge of the molecular mechanisms underlying these processes may contribute significantly to our understanding of recurrence and metastasis in human cancer.